Compensating cam and spring balance for x-ray devices



A. J. FODERARO March 3, 1959 COMPENSATING CAM AND SPRING BALANCE FOR X-RAY DEVICES Filed Sept. 10, 1956 s Sheets-Sheet 1 INVENTOR. i/vr/xa/vrl' FOOE/FlY/FO ad fl/Zw a $9 March 3, 1959 A. J. FODERARO COMPENSATING CAM AND SPRING BALANCE FOR X-RAY DEVICES Filed se t'l 10, 1956 5 Sheets-Sheet 2 INVENTOR. filVTfi/ON) J'Faoszvamo BY ,7%@/fi a? 15420.. I

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United States Patent COMPENSATING CAM AND SPRING BALANCE FOR X-RAY DEVICES Anthony J. Foderaro, Middleburg Heights, Ohio, assignor to Picker X-Ray Corporation Waite Manufacturing Division, Inc., Cleveland, Ohio, a corporation of 01110 Application September 10, 1956, Serial No. 608,948

Claims. (Cl. 250-91) This invention relates to a counterbalancing construction and more particularly to a counterbalancing construc- 2,876,362 Patented Mar. 3, 1959 ice 5 with the head supporting cable omitted; while tion for an X-ray head supported by a ceiling-mounted tube stand.

One of the objects of the present invention is to provide a means for compensating for a variable counterbalancing force acting against gravity upon a variable weight so that the weight will be approximately counterbalanced over the entire range of raising and lowering movement.

A further object of the present invention is to provide a counterbalancing construction of the type set forth in the previous paragraph including a spring providing the variable force and a spiral sheave or compensating cam providing the compensation desired.

A further object of the present invention is to provide a counterbalancing construction wherein a plurality of so that the counterbalancing construction will permit raising and lowering of the X-ray head with a minimum effort.

A further object of the present invention is to provide a counterbalancing construction characterized byits structural simplicity, ease of operation, and compensation for v a plurality of variables.

Other features of this invention reside in the arrangement and design of the parts for carrying outtheir appro- Other objects and advantages of this invention will be apparent from the accompanying drawings and description and the essential features will be set forth in the appended claims.

In the drawings: Fig. 1 is a side elevational view of ceiling tube stand and counterbalanced X-ray head in the present invention with the head being in its most extreme lowered position;

the component parts in the head-raised position corresponding' to Fig. 2; b y I Fig. 5 is a horizontal sectional view taken along the line 5-5 of Fig. 2 through the component parts of the counterbalancing construction;

, Fig. 6 is a vertical sectional view taken along the line 6-6 of Fig. 5 through the counterbalancing construction with the head in the lowered position of Fig. l;

I Fig. 7 is a vertical sectional view taken along the line 7-7 of Fig. 1 through the connection between head and the counterbalancing cable;

the X-ray Fig. 9 is a graph showing in solid line the downward force exerted by the X-ray head and tubes carried thereby upon the cables in Fig. 7 and in dotted line the upward force exerted by the cables upon the head.

Before the counterbalancing construction here illustrated is specifically described, it is to be understood that the invention here involved is not limited to the structural details or arrangement of parts here shown since counterbalancing constructions embodying the present invention may take various forms. It also is to be understood "that the phraseology or terminology herein employed is for purposes of descripti'on'and not of limitation since the scope of the present invention is denoted by the appended claims.

While the present invention may be adapted to various uses, it has been chosen to show the same as applied to a ceiling-mounted tube stand for an X-ray head of a type, described and claimed in the copending U. S. patent application filed by Ralph R. Schiring and Edgar J. Bastin on July 8, 1954 entitled Tubular Telescopic Column and given Serial No. 441,994; although the present invention may be applied to a vertically extending tubular column having a plurality of interfitting telescopic parts of any suitable construction.

The X-ray head corresponds closely to that found in the copending application. Head 11 in Fig. 1 includes a tubular member 12 through which extends a hollow tubular axle having a bracket 14 at one end and a suitable focusing light 13 either at the same end or at the other end, as illustrated. Bracket 14 carries the X-ray tube itself, as indicated at 15. Bracket 14 and X-ray tube 15 are rotatable about the tubular axle while X-ray tube 15 is also oscillatable through another plane about bracket 14.

X-ray head 11 is supported by a ceiling tube stand in cluding a base 17 and a tubular column 18 extending downwardly therefrom. Base 17 is mounted by suitable rollers for movement horizontally along channels 19 in one direction, and along track members 20 in a second horizontal direction perpendicular to said first movement in. the mannerdisclosed in the aforesaid copending application. This construction supports the upper side 17a of base 17 parallel to the flat room ceiling 22 to which are secured track members 20 with channels 19 secured thereto by suitable rollers.

Tubular column 18 includes a plurality of telescopically related tubes 24, 25, 26, 27, 28 and 29 either having the specific construction shown in the aforesaid copending application, the simplified construction in Fig. 8, or other suitable construction. The balls, designated 40 in the copending application and which prevent relative rotation between adjacent sleeves, are omitted in Fig. 8 for clarity, since the balls are so small. Each tube is of basically the same construction in the simplified form in Fig. 8 with an outwardly extending annular flange 27a on one end and an inwardly extending annular flange 27b at the other end. The lower end of tube 29 is secured to X-ray head member 12 while upper tube 24 is telescopically movable within either a tube secured directly to base 17 or a bore in thelower surface of base 17 and has its outwardly ex tending annular flange at its upper end adapted to engage against the upper surface of the bore in base 17 to prevent downward disassembly of tube 24 from base 17 and to support the lower tubes in the manner shown by tubes 26 and 27 in Fig. 8 by the interlock between the adjacent flanges on adjacent tubes.

X-ray headll is supported by cable 31, 32 through a clevis-type connection shown in Fig. 7. In Fig. 7, cap 33 is secured to member 12 over the connection between the extension 12a of member 12 and tube 29. Pivot pin 35 pivotally connects clevis 36 to extension 12a with the clevis 36 including a U-member 36a, bolt 36b and adjustment nut 36c. A plate 38 is telescopically associated over the shank of bolt 361) with cable connectors 39, 39 extended therethrough with each having a threaded shank, lock nuts, and shock absorbing spring.

This construction permits head 11 to 'be raised and lowered in opposite directions relative to base 17 while being suspended therefrom and located therebelow. Raising and lowering is achieved by respectively applying an upward force to cable 31, 32 or by paying out this cable to lower head 11. The Weights of tubes 24-29 are sequentially transferred from head 11 upon which they are nested to base 17 during lowering of head 11 from the Fig. 2 to the Fig. 1 position and then transferred from base 17 back to head 12 during head raising, as will be readily apparent upon consideration of Fig. 8 and the coaction between the annular flanges on adjacent ends of adjacent tubes.

Means is provided for approximately counterbalancing the weight of X-ray head 11 and the weight of tubes 24-29 transferred to head 11 in all head suspended positions over the entire range of raising and lowering movement from the Fig. 1 to the Fig. 2 position. Hence, the fixed weight of head 11 and the weights of the added tubes are approximately counterbalanced in each position. Head 11 may be raised and lowered by hand with minimum eifort, instead of by the motor disclosed in the copending application, by gripping and moving up or down handles 15a carried by X-ray tube 15. The head 11 will stay in its raised or lowered position because of the accurate counterbalance. The counterbalance construction disclosed herein is a spring means actuated force pulling upwardly on cable 31, 32 so that the construction must not only compensate for the variation in weight caused by the addition of one or more tubes 24-29 to head 11 but also for the variable counterbalancing force exerted by the spring means.

Base 17 includes within its outer shell suitable framework for supporting this counterbalancing means. This framework includes a plate 41 in Figs. and 6 secured to upstanding bosses in the shell of base 17 by screws with plate 41 having welded thereto upstanding walls 43, 45 and 47, and a depending wall 49. Wall 49 has brackets 51 and 53 welded thereto with the cable block 55 welded or otherwise secured to bracket 51.

The counterbalance includessuitable spring means for exerting the counterbalancing force. This takes the form in the present construction of a plurality of springs 60 connected in parallel, here shown as: four in number, arranged in a plane generally parallel to the upper base side 17a so that they may be mounted in minimum space and the base will not protrude downwardly unduly far from the ceiling. Each spring 60 is secured at opposite ends to base wall 43 by connection 69a and to a carrier 62 by connection 6%. A plurality of sheaves are .provided with sheaves 69 and 70 rotatably carried by a shaft on carrier 62 and sheave 71 rotatably carried by block 55. The cable 67, comprising two parallel cable sections, is secured at one end to block 55; is trained successively over sheaves 69, '71 and 78; and is secured at its other end to a drum 65 keyed to shaft 64 rotatably supported in brackets 51 and 53. Hence, this cable and sheave construction multiplies the movement of springs 60 in rotatably driving shaft 64. i

Compensation for the variable force exerted by springs 60 and for the variable weight carried. by cable 31, 32 is provided by a spiral sheave 74 secured to the outer end of shaft 64. The spiral sheave has a conical periphery to serve as a compensating cam. Cable 31, 32 of Fig. 7 extends upwardly through the tubes 24-29 of tubular column 18, extends through and over-a pivot pulley 78, is wound around spiral sheave 74, and has its end secured to the largest diameter of the sheave 74. Pivot pulley 78 includes a bracket 79 either fixed to plate 41 or mounted for oscillation about a vertical axis on plate 41 around the hole therein through which cable 31, 32 downwardly extends. Sheave 80 is rotatably carried by this pivot pulley unit 78. This oscillation permits sheave 80 to be swung into alignment with any step on sheave 74 by cables 31 and 32.

The operation should now be readily apparent. When head 11 is in the lowered position of Fig. l, the counterbalancing construction is in the positions shown in Figs. 3 and 6 with cable 31, 32 on the largest diameter step of spiral sheave 74. When handles 15a are grasped and the head 11 is manually raised to the Fig. 2 position, the parts then assume the positions shown in Figs. 4 and 5 with cable 31, 32 trained over the smallest diameter step of spiral sheave 74. If head 11 is stopped in any intermediate position, it will be approximately counterbalanced. vAlso, raising and lowering requires little effort because of the counterbalance. Fig. 9 illustrates graphically the forces in this operation. The dotted line curve in Fig. 9 portrays the upward force exerted on cable 31, 32 by the variable force exerted by springs 60 through cable 67 to rotate drum 65 and spiral sheave 74. The stepped solid line curve illustrates the weight pulling downwardly on cable 31, 32 by the fixed weight of head 11 and the weights of the tubes 24-29 sequentially trans- {erred in steps from head 11 to base 17 during head lowering and from base 17 to head 11 during head raising. The weight counterbalanced varies from 89 pounds in the Fig. 1 position to 111 pounds in the Fig. 2 position in one embodiment of my invention. The design of the spiral sheave 74 is a critical factor compensating for the variation in the force of springs 60 and in the weight of head 11 and the tubes carried thereby. It has been found for this particular installation that the spiral sheave 74 has a cone apex angle of 364 /2' with respect to its axial center line and a pitch of 0.379 inch measured parallel to the central axis between corresponding points on adjacent cable grooves.

It should be readily apparent that in its broadest aspects this counterbalancing construction may be used in other types of apparatuses. It may be used in any installation wherein a variable force is used to counterbalance a variable weight. For example, the variable weight may be achieved by any means responsive to the movement of a fixed weight, such as head 11, in either .a raising or lowering direction for adding weight increments, such as tubes 24-29, to this fixed weight at predetermined intervals during this movement in one direction and subtracting these added weight increments during movement in the opposite direction.

It has been found desirable to provide a suitable locking device to lock the component parts in any given position of elevation and to prevent upward and downward movement of head 11. This takes the form of an electromagnetic lock with two electromagnets in Fig. 5 carried by base 17 and adapted to brake against a disc carried by sheave 74. When the lock is engaged, it will lock head 11 against accidental vertical movement which might change the vertical distance between the X-ray head 11 and the target. Since the head 11 is fairly accurately counterbalanced, accidental movement thereof may easily take place if a locking device is not provided. Also, it should be noted in Fig. 9 that the dottedv line and solid line curves intersect at approximately the mid-point of each step so that a complete counterbalancing will occur only at these points. Although this type curve intersection provides a minimum amount of unbalanced weight in the worst unbalance position, some unbalance will still be present because the curves do not coincide. Frictional drag of the component parts will compensate for some of this weightnot counterbalanced. However, the locking by the lock '85 will prevent any movement which may still tend to occur because of the weight not counterbalanced and not overcome by the frictional drag.

For convenience of the X-ray machine operator, a suitable control panel in Fig. 2 is provided on X-ray tube immediately adjacent the raising and lowering handles 15a. Button 15b turns focusing light 13 on and ofi, buttons 15d and 15a actuate lock brakes for respective movement along channels 19 and track members 20, and button 150 energizes and deenergizes electric brake 85 to lock head 11 against vertical movement.

A suitable indicating device is provided for indicating the vertical distance between head 11 and base 17 or the vertical distance between X-ray tube 15 and its target in any particular installation. Here, a drum 80a is rotatable coaxially with sheave 80 and drives an endless cable 86 trained around sheaves 87, 87 and indicating sheave 89 with each of these sheaves rotatably mounted on plate 4. Indicating sheave 89 has secured to its shaft for rotation therewith an indicia wheel 90 with the numbers thereon adapted to be read from the floor below base 17 by the X-ray operator through openings 17a in base 17. Hence, as head 11 moves up and down, indicia wheel 90 will rotate until the appropriate height indicating numbers thereon are respectively in alignment with an indicator on base 17 and are readable through opening 17a.

It will be noted that cables 31 and 32 are reaved in parallel over duplicate sets of grooves in sheaves or pulleys 74 and 80, so that if one cable breaks, the other is still operative. For a like reason cable 67 is duplicated over pulleys 69, 71 and 7t), and both cables are attached to drum 65.

Various changes in details and arrangement of parts can be made by one skilled in the art without departing from either the spirit of this invention or the scope of the appended claims.

What I claim is:

1. In a ceiling tube stand for an X-ray head, a base, an X-ray head located below said base and suspended therefrom and adapted to be raised and lowered by movement in opposite directions relative to said base, a plurality of telescopically related tubes operatively connecting said base and head and constructed so that the weights of said tubes are sequentially transferred from said head to said base during head lowering and from said base to said head during head raising, and means for approximately counterbalancing the weight of said head and the tubes transferred to said head in all head suspended positions over the entire range of raising and lowering movement.

2. In a ceiling tube stand for an X-ray head, a base, an X-ray head located below said base and suspended therefrom and adapted to be raised and lowered by movement in opposite directions relative to said base, a plurality of telescopically related tubes operatively connecting said base and head and constructed so that the weights of said tubes are sequentially transferred from said head to said base during head lowering and from said base to said head during head raising, and means for approximately counterbalancing the weight of said head and the tubes transferred to said head in all head suspended positions over the entire range of raising and lowering movement, said last mentioned means including spring means secured at one end to said base and a spiral sheave 0peratively connected between said spring means and head to compensate for the variation in spring force and in weight of said head and tubes carried thereby.

3. in a ceiling tube stand for an X-ray head, a base having one side adapted to be supported parallel to a flat ceiling, an X-ray head located below said base and suspended therefrom and adapted to be raised and lowered by movement in opposite directions relative to said base, and means operatively connecting said base and head for approximately counterbalancing said head in all head suspended positions over the entire range of raising and lowering movement, said last mentioned means including a plurality of springs arranged in a plane generally parallel to said one base side for mounting in minimum space in said base.

4. In a ceiling tube stand for an X-ray head, a base having one side adapted to be supported parallel to a flat ceiling, an X-ray head located below said base and suspended therefrom and adapted to be raised and lowered by movement in opposite directions relative to said base, and means operatively connecting said base' and head for approximately counterbalancing said head in all head suspended positions over the entire range of raising and lowering movement; said last mentioned means including a carrier, spring means secured at opposite ends to said base and said carrier, a plurality of sheaves with some carried by said carrier and others carried by said base, a spiral sheave adapted to raise and lower said head and to compensate for the variation in spring force, and a cable trained over said sheaves in a plurality of runs to multiply the movement of said spring means and to rotatably drive said spiral sheave.

5. In a ceiling tube stand for an X-ray head, a base having one side adapted to be supported parallel to a flat ceiling, an X-ray head located below said base and suspended therefrom and adapted to be raised and lowered by movement in opposite directions relative to said base, a plurality of telescopically related tubes operatively connecting said base and head and constructed so that the weights of said tubes are sequentially transferred at predetermined intervals from said head to said base during head lowering and from said base to said head during head raising, and means for approximately counterbalancing the weight of said head and the tubes transferred to said head in all head suspended positions over the entire range of raising and lowering movement; said last mentioned means including a carrier, a plurality of springs arranged in a plane generally parallel to said one base side for mounting in minimum space in said base with each spring secured at respective opposite ends to said base and said carrier, a plurality of sheaves with some carried by said carrier and others carried by said base, a spiral sheave adapted to raise and lower said head and to compensate for the variation in spring force and in weight of said head and tubes carried thereby, and a cable trained over said sheaves in a plurality of runs to multiply the movement of said springs and to rotatably drive said spiral sheave.

References Cited in the file of this patent UNITED STATES PATENTS 169,430 Fox Nov. 2, 1875 249,057 Johnson Nov. 1, 1881 2,659,827 Scag et a1. Nov. 17, 1953 2,737,596 Haupt et a1. Mar. 6, 1956 

